I'm new to boat motors, but consider myself mechanically inclined. 
The motor, as mentioned, is a Mercury V6 150HP. I believe it's an '89 model, but I'm not positive. I've read up on a lot of "how to test a stator, power pack (aka switchbox), spark, and coil", so I think I've come to a conclusion of what is wrong and I'm hoping someone can advise as well. Btw, I can't seem<br />to find the ID of the engine, however, I do see<br />the number 15988334 on the leg; can't seem to<br />reference it to anything.<br /><br />Problem:<br /><br />The boat is a downright DOG when I first take it out. At full throttle the RPMs won't go past around 2000. However, outside of the water I can definitely rev up to 4000/5000rpm. After about 15-20 minutes of "full" throttle (lever is fullly forward, but still 2000rpm), the engine seems to come alive and then I'm able to throttle up to 4000/5000rpm. I've read that it could be a faulty coil, switchbox, trigger and stator, and the warming up of the engine temporarily fixes the problem.<br /><br />Diagnostics:<br /><br />I've only done a spark gap test, but what I've found "seems" to point to the switchbox. The spark gap test seems to be good for all of the cylinders except for #6. Cylinder #6 has no spark. I swapped the #6 and #4 coil input wires on the switchbox and noticed that cylinder #6 now has spark and cylinder #4 doesn't anymore; this ruled out that coil #6 is bad. Since I only have one switchbox, my thinking is that the stator is good because the other cylinders pass the spark gap test. Is my assessment of the switchbox being bad correct? Also, I only notice one switchbox<br />and it appears to be a 18-5775. SHouldn't there<br />be two??<br /><br />Thanks for all replies,<br /><br />Rey
The motor, as mentioned, is a Mercury V6 150HP. I believe it's an '89 model, but I'm not positive. I've read up on a lot of "how to test a stator, power pack (aka switchbox), spark, and coil", so I think I've come to a conclusion of what is wrong and I'm hoping someone can advise as well. Btw, I can't seem<br />to find the ID of the engine, however, I do see<br />the number 15988334 on the leg; can't seem to<br />reference it to anything.<br /><br />Problem:<br /><br />The boat is a downright DOG when I first take it out. At full throttle the RPMs won't go past around 2000. However, outside of the water I can definitely rev up to 4000/5000rpm. After about 15-20 minutes of "full" throttle (lever is fullly forward, but still 2000rpm), the engine seems to come alive and then I'm able to throttle up to 4000/5000rpm. I've read that it could be a faulty coil, switchbox, trigger and stator, and the warming up of the engine temporarily fixes the problem.<br /><br />Diagnostics:<br /><br />I've only done a spark gap test, but what I've found "seems" to point to the switchbox. The spark gap test seems to be good for all of the cylinders except for #6. Cylinder #6 has no spark. I swapped the #6 and #4 coil input wires on the switchbox and noticed that cylinder #6 now has spark and cylinder #4 doesn't anymore; this ruled out that coil #6 is bad. Since I only have one switchbox, my thinking is that the stator is good because the other cylinders pass the spark gap test. Is my assessment of the switchbox being bad correct? Also, I only notice one switchbox<br />and it appears to be a 18-5775. SHouldn't there<br />be two??<br /><br />Thanks for all replies,<br /><br />Rey